1. Field of the Invention
The present invention relates to a photographic film splicer and a method of splicing photographic films in which leading and trailing ends of a plurality of photographic films are joined together by hot-melt adhesive tape, with predetermined intervals being provided between the joined leading and trailing ends, so as to form a longer connected body of a plurality of photographic films.
2. Description of the Related Art
Splicers are used in large-scale developing facilities in order to efficiently carry out developing processing, printing processing and the like. Approximately 50 to 100 films are joined by splicing tape so as to form an elongated body, and are processed in this state.
When processing of the films has been completed, the regions to which tape is adhered are removed and the elongated body is divided into the respective films. Each of the films is cut into a predetermined number of frames (e.g., six frames) such that piece negatives are formed. Thereafter, the piece negatives are accommodated in accommodating bodies known as negative sheets, and are returned to the customer in this state.
U.S. Pat. Nos. 4,834,306 and 4,846,413 and Japanese Patent Application Laid-Open No. 3-37645 have proposed a new type of photographic film cartridge in which the cartridge main body is formed as a resin molded product and in which the photographic film is delivered out to the exterior of the cartridge main body due to the rotation of a spool.
This new type of photographic film cartridge differs from its predecessors in that the leader portion of the photographic film does not protrude out from the cartridge main body either before the photographic film cartridge has been used or after the cartridge has been used. Accordingly, advantages are obtained in that the photographic film can be accommodated so as to be shielded from light even more than before, and the handling of the photographic film cartridge before and after use thereof is quite easy.
In order to enable reuse of this new type of photographic film cartridge, as opposed to cutting the trailing end portion as in the case of conventional 135 films, the trailing end of the photographic film is engaged with the spool within the cartridge main body, and the photographic film is separated from the cartridge by this engagement being canceled by a special jig used for such a purpose. As with conventional photographic films, it is preferable to join 50 to 100 of these separated photographic films by splicing tape so that processing thereof can be carried out efficiently.
Here, in order to return the processed or developed photographic film to the customer in a state in which the photographic film is rewound within the cartridge, it is necessary to maintain a specially-machined portion at the trailing end portion of the photographic film so that the trailing end portion can engage with the spool again.
However, as in conventional means, when the splicing tape adhered region of the photographic film for which processing has been completed is cut, the trailing end portion of the photographic film having such a specially-machined portion (i.e., a portion machined to allow engagement of the trailing end portion with the spool) is also cut. Accordingly, the trailing end portion cannot engage with the spool.
As a result, a desplicer has been proposed which is disposed between separatable photographic films and which does not cut the leading and trailing ends of two photographic films joined by splicing tape.
At this separating device, only the portion of the tape at a joining portion at which two photographic films are joined is nipped at a predetermined pressure. When the tape is heated and the paste melts, the films are pulled in directions of moving apart from the tape and are separated therefrom. Therefore, when such a separating device is used, the two films must be joined such that there is a predetermined gap therebetween in the center of the joined portion, which gap is a portion at which only the tape is nipped.
As illustrated in FIG. 12, a conventional splicer 100 for 135 film includes a heating head 102 which moves up and down, and a pad 104 which opposes the heating head 102. The pad 104 is formed from a fluoroplastic or the like in consideration of the heat resistance thereof and the relative ease with which tape can be peeled therefrom.
When two photographic films 106 are joined, the leading end of one photographic film 106 and the trailing end of another photographic film 106 are set on the pad 104. Splicing tape 108 is pressed and heated by the heating head 102. The paste on the splicing tape 108 thereby melts and adheres to the photographic films 106. At this time, the interval a the time of joining is a small gap of around 0.5 to 1.5 mm. Therefore, the portion of the splicing tape 108 which is positioned between the two photographic films 106 and which is not adhered to the photographic films 106 (i.e., the portion at the interval a) does not contact the pad 104, and the splicing tape 108 does not adhere to the pad 104.
However, if the interval a between the leading end of the one photographic film 106 and the trailing end of the other photographic film 106 is widened more than before, when the splicing tape 108 is heated and pressed, the portion of the splicing tape 108 between the respective end portions of the photographic films 106 which portion does not contact the photographic films 106 adheres to the pad 104 as shown in FIG. 13, and the photographic films 106 cannot be conveyed after being joined. This may be due to the fact that the splicing tape 108 is pressed against the pad 104 because high pressure is applied thereto (e.g., 50 to 200 kg).
Further, in the splicer 100 for 135 films, the joined portion is positioned by the number of perforations being counted and conveying being stopped at a predetermined position.
However, the intervals between the perforations in a photographic film used in the new type of photographic film cartridge are wide, and perforations are only formed in the vicinities of the image frames. Further, the perforations correspond to the image frames, and the respective distances from the perforations to the leading and trailing ends of the films are not always precise. Moreover, the respective configurations of the leading ends and the trailing ends of such photographic films are complex, and positioning cannot be effected by counting the number of perforations. It is extremely difficult to accurately position the leading ends and trailing ends of the films when also taking into account the meandering of the photographic films during the conveying thereof.